The present invention relates to toothbrushes in general, and more particularly to improvements in composite toothbrushes of the type wherein the bristle carrying member (hereinafter called carrier or bristle carrier for short) is separable from the handgrip (hereinafter called handle).
It is already known to assemble a toothbrush from two separable pieces one of which constitutes the handle and the other of which carries the bristles. Such pieces have confronting end faces and the end face of the carrier has a socket for a projection which extends from the end face of the handle. The socket is surrounded by the material of the carrier at all sides except at the end face of the carrier. An advantage of a composite toothbrush is that the handle can be reused when the wear upon the bristles has progressed to an extent such as to warrant dispensing with the carrier and its replacement by a fresh carrier. Frequent replacement of carriers with unsatisfactory or worn bristles is desirable for hygienic as well as for medical reasons. Furthermore, it is possible to utilize an elaborate, decorative and reasonably expensive handle because it need not be discarded with the bristle carrier.
Published European patent application Ser. No. 0 083 787 discloses a composite toothbrush which employs a metallic handle. The rear end of the handle is embedded in a synthetic plastic knob. The knob and the handle are secured to each other with a force which suffices to allow for safe manipulation of the handle when the toothbrush is in use. The front end portion of the handle extends into a socket of the bristle carrier and is held therein by friction and/or by clamping action. Mere frictional and/or clamping engagement is often insufficient to prevent undesirable separation of the bristle carrier from the handle when the toothbrush is in actual use. For example, if the front end portion of the handle is held in the socket merely by friction, the magnitude of friction tends to decrease in response to repeated use of the toothbrush and attendant movements of the front end portion of the handle relative to the carrier. Since the handle is made of a metallic material, its front end is likely to hurt or even injure the mouth of the user in response to undesired segregation of the bristle carrier from the handle.
German Utility Model No. 84 28 969 discloses a different coupling between the front end portion of the handle and the bristle carrier of a two-piece toothbrush. The coupling includes a dovetailed male portion at the front end of the handle and a complementary socket in the bristle carrier. In addition, the German Utility Model discloses a small projection which can enter a recess to enhance the reliability of the coupling which is constituted by the male member and the socket. The bristle carrier has a substantially U-shaped outline and its legs flank the male coupling member. Such design is unsatisfactory because the bristle carrier is relatively weak and is likely to expand so that the male coupling member can be extracted from the space between the legs with attendant undesirable separation of the bristle carrier from the handle. Moreover, the aforementioned projection and the recess therefor do not contribute appreciably to reliability of the connection between the handle and the bristle carrier.